Microelectromechanical (MEM) resonators are useful to form oscillators and filters. Of particular interest are MEM resonators which utilize a layer of a piezoelectric material and operate in a contour mode. In such contour-mode MEM resonators, the piezoelectric material expands and contracts in a direction parallel to the layer in response to an applied voltage of oscillation, with the resonant frequency being generally determined by a lateral dimension (e.g. a width or length) of the MEM resonator. Since the resonant frequency does not depend upon a thickness of the layer of piezoelectric material, but instead depends on its width or length, then a plurality of MEM resonators having different resonant frequencies can be fabricated on a common substrate and used, for example, as a channel-selection filter. A particular difficulty heretofore has been that each resonant frequency can be well-defined in theory, but not in actuality since fabrication of the MEM resonators relies on conventional micromachining processes which utilize photolithographic reticles (also termed masks) having a fixed granularity due to a predetermined grid size G of the reticles. Specially fabricating a new set of photolithographic reticles with a different grid size G, which is specifically tailored to each MEM resonator, is costly so what is needed is a way of fabricating one or more MEM resonators based on a single set of photolithographic reticles having a fixed grid size G while providing an actual resonant frequency in the fabricated MEM resonators which is close to a desired resonant frequency.
The present invention addresses this limitation in the prior art by providing a method for fabricating one or more MEM resonators with dimensions of various elements in each MEM resonator being determined in terms of integer multiples of the grid size G so that the actual resonant frequency and other parameters of each MEM resonator are closer to initially specified values than is currently possible using conventional fabrication methods.
These and other advantages of the present invention will become evident to those skilled in the art.